1. Field of the Invention
The present invention relates to a device for detecting an environmental abnormality such as a gas leakage or a fire and providing an alarm signal.
2. Description of the Prior Art
Conventionally, a monitoring device for fire, gas, or the like detects temperature, smoke density, and gas concentration and produces an alarm when the detected level reaches a predetermined value. In general, the number of sensors is determined in accordance with the floor area of a room to be monitored. Detection signals obtained from sensors are discriminated by a single reference value so that an abnormality is detected regarding the overall detection area as a single area. In some devices, a central monitoring unit performs total abnormality discrimination from detection signals (analog signals) of a plurality of sensors, however, temperatures and smoke densities are measured and discriminated by a single measure.
As described above, a monitoring device for fire, gas, or the like performs discrimination of a fire or a gas leakage by detection signals of one or more sensors. Levels of a fire or a gas leakage are detected for the overall detection area. If sensing areas for respective sensors differ from each other, an alarm cannot be produced according to differences in scale of a fire or a gas leakage. If a fire is to be detected by temperature, for example, sensors are provided in units of predetermined floor areas, however the heights of the respective ceilings to which each sensor is attached may be different. Fires of an identical scale will thus be detected as fires of different levels in accordance with locations of fires and an alarm may be delayed.